Experimental and numerical analysis of the hygric performance of earthen buildings after façade hydrophobization treatment

Earth is used extensively for buildings worldwide, as its thermal properties contribute to a favorable indoor thermal environment. However, earthen materials are sensitive to moisture ingress, which can result in structural damage and undesirable indoor humidity conditions. Through hydrophobization treatment, the capillarity of earth can be significantly reduced while hygroscopicity remains largely unchanged, thereby possibly improving the hygric performance of earthen buildings. In the present study, experiments and simulations were conducted to investigate the effect of hydrophobization on earthen materials and buildings. The experimental results show that the bulk density, open porosity, and pore-size distribution of rammed earth changed by only a few percent after hydrophobization treatment. The thermal properties (thermal conductivity, specific heat capacity, solar reflectivity and longwave emissivity) and hygroscopic properties (sorption isotherm and water vapor permeability) also showed limited changes (